"Our findings show that 13-month-olds can make sense of social situations using their understanding about others' minds and social evaluation skills," said psychological scientists and study authors You-jung Choi and Yuyan Luo from University of Missouri.

For the study, the researchers brought 48 infants, who were around one-year old, into the lab for their experiment.Two puppets (A and B) appeared on stage and clapped their hands or hopped around together, allowing the infants to familiarise themselves with the characters and learn that A and B were friendly with each other.

Then, the infants were presented with a particular social scenario.In one, the infants saw a third puppet, C, approached and get deliberately knocked down by B, as A looked on from the side.In another scenario, B knocked down C, but A was not present. And in a third scenario, C was accidentally knocked down as A looked on.

The researchers found that the infants responded to outcomes in the three scenarios differently, in accordance with the social implications of each scenario.

Infants cannot tell us what they expect to happen, so the researchers turned to looking time as a way of getting at infants' expectations.

Things that were normal or expected were relatively boring and infants quickly looked away, but things that were unusual or unexpected, however, were interesting and infants spent more time looking at the novel thing.

So, if A was a witness to the deliberate hit, the infants seemed to expect A to shun B."This to us indicates infants have strong feelings about how people should deal with a character who hits others," the researchers noted.